(+)-カテキン水和物

解説カテキン，3,3′,4′,5,7-pentahydroxyflavan．C15H14O6(290.27)．樹木に広く含まれていて，多くのタンニンの母体となっている．カテキン分子の2位と3位の炭素原子は不斉炭素原子で，d-カテキン，l-カテキン，d-エピカテキン，l-エピカテキンの4種類の立体異性体が存在する．カテキンとエピカテキンは互いにジアステレオマーの関係にある．Uncaria gambirより得られるものはd-カテキンで，融点175 ℃．[α]D18＋18.5°(水溶液)．λmax 280 nm．水に易溶，エタノール，酢酸エチルに可溶．dl-カテキンは融点212～214 ℃．主として，染色，なめし革関係で用いられる．顕著な抗菌，抗酸化作用がある．また，l-エピカテキンはAcacia catechuから得られ，融点245 ℃．[α]D－68°．

用途カテキンには実に多様な生理活性があることが報告されており、それらを列挙すると、血圧上昇抑制作用、血中コレステロール調節作用、血糖値調節作用、抗酸化作用、老化抑制作用、抗突然変異、抗癌（食道癌、胃癌、大腸癌、結腸癌、膵臓癌、肺癌、前立腺癌、乳癌、膀胱癌）、抗菌、抗う蝕、抗アレルギー作用などとなる。チャノキの抽出物は米国でシネカテキンスとして、性器ヘルペス（HPVウイルス）の治療に承認されている。

使用Cianidanol, also known as (+)-catechin; (+)-3,3′4′,5,7-flavanepentol; 3,3′,4′, 5,7-pentahydroxyflavane, [R,3S]-2-[3,4-dihydroxyphenyl]-3,4-dihydro-1[2H]- benzopyran-3,4,7-triol, or 2-(3,4-dihydroxyphenyl)-3,4-dihydro-(2r-trans)-2h- 1-benzopyran-7-triol, is a flavonoid associated with a variety of blood disorders. An association of cianidanol and immune hemolytic anemia and thrombocytopenia has been suggested in numerous case reports. In several reports, the presence of flavonoid-dependent antibodies against red blood cells is evident with cianidanol combining with erythrocyte membranes and inducing development of autoantibodies and antibodies.Several patients had platelet antibodies with increased serum-bindable IgG values without the presence of cianidanol and several with high platelet-associated IgG levels.Antibodies against cianidanol were not detectable in certain cases.The hemolytic anemia caused acute renal failure in some patients and can be life threatening, leading to fatalities. Upon cessation of treatment with cianidanol, hematology appears to return to normal over time.These side effects do not appear to be specific to cianidanol as the formation of IgE and IgG antibodies to troxerutin (Venoruton) and silymarin (Kegalon) was also evident with patients presenting with fever, skin eruptions, and intravascular hemolysis often demonstrating high IgG titers.Furthermore, cianidanol-induced hemolysis might also occur after sensitization by other flavonoids including rutin.

一般的な説明(+)-Catechin is an important beneficial compound, belonging to the flavonoid class, which is present abundantly in red wine.